Method and server for dynamically determining a reference signal (RS) power boost level

ABSTRACT

A method and application server for dynamically determining a Reference Signal (RS) Power Boost level in a radio telecommunication network. The application server may be a Self-Optimized Network (SON) application server configured to received network performance information from Performance Management (PM) counters and configuration information from a configuration database server. The application server monitors a plurality of network Key Performance Indicators (KPIs), compares the KPIs to associated thresholds, and derives and assigns values to KPI threshold factors. The server calculates a scaling factor based on values of the KPI threshold factors, and calculates a dynamic RS Power Boost level by applying the scaling factor to a baseline RS Power Boost level.

TECHNICAL FIELD

The present disclosure relates generally to communication systems andmore particularly to a method of dynamically determining a ReferenceSignal (RS) Power Boost level in a radio telecommunication network.

BACKGROUND

A Reference Signal (RS) is a symbol used for Channel quality estimationand coherent demodulation in the downlink. To demodulate differentdownlink physical channels coherently, a User Equipment (UE) requirescomplex valued channel estimates for each subcarrier.

In the Long Term Evolution (LTE) radio access network, known referencesymbols are inserted into a time-frequency resource grid. The referencesignal is mapped to resource elements spread evenly in the resourcegrid, in an identical pattern in every resource block.

FIG. 1 is a diagram depicting time-frequency resource grids with typicalCell-specific Reference Signal (CRS) positions for one-antenna port andtwo-antenna port configurations. When transmitting with severalantennas, each antenna must transmit a unique reference signal. When oneantenna transmits its reference signal, the other antenna must besilent, as shown by the Xs in the reference symbol locations. Themapping of the reference signal on the resource grid therefore dependson the antenna configuration. The pattern of reference signals can beshifted in frequency compared to FIG. 1. Which one of the six possiblefrequency shifts to use depends on the Physical Cell Identity (PCI) senton the Primary Synchronization Signal (PSS) and the SecondarySynchronization Signal (SSS).

In the conventional LTE System, the Cell Specific Reference Signal (CRS)power can be provisionally boosted by 3 dB when an RS Power Boostparameter is enabled by making use of the unused power available due tothe corresponding silent resource element. The unused power of thesilent resource element can be added to the reference signal resourceelement when the RS Power Boost parameter is enabled. This in turn leadsto a 3 dBb boost of the Reference Signal Resource Element Power incomparison to the default value.

The existing method of CRS Power Boost by 3 dB or any other fixed valuemay unnecessarily increase the CRS footprint of the RS PowerBoost-enabled Cell Site which could possibly degrade the radio networkperformance due to several reasons. First, the existing method maydegrade the cell-edge performance of an overlapping cluster of cellsites by becoming a potential interferer due to the higher degree ofoverlap with its neighboring cell site clusters. Second, the existingmethod may increase the handover failure rate to same or legacytechnologies. Third, the existing method may potentially reduce theaverage cell-site throughput and the connected user capacity if thepower boost leads to covering unwanted far-off users operating in alower order modulation and coding scheme (MCS) and in transmitdiversity, i.e., Multiple Input Multiple Output (MIMO) schemes with agreater number of retransmissions than before. Fourth, the existingmethod may increase the Uplink (UL) Received Signal Strength Indicator(RSSI), i.e., the uplink noise and interference level which canpotentially degrade the uplink throughput performance. Fifth, theexisting method may increase the Random Access Channel (RACH) failurerate due to coverage imbalance between the UL and DL.

SUMMARY

It is an object of the present disclosure to optimize network resourceutilization by mitigating the above situations arising due to the use ofa static 3 dB RS power boost value. In different embodiments, thepresent disclosure considers several network performance factors inorder to dynamically determine a varying level of RS power boost. Thesefactors may consider coverage, capacity, and quality indicators todynamically determine an optimal level of RS power boost level, therebystriking a proper balance between interference level and coveragereliability at the cell edge.

According to a first embodiment, a method performed in an applicationserver for dynamically determining a Reference Signal (RS) power boostlevel in a radio telecommunication network is provided. The methodincludes monitoring a plurality of network performance indicators;calculating a scaling factor based on values of the plurality of networkperformance indicators; and calculating a dynamic RS Power Boost levelby applying the scaling factor to a baseline RS Power Boost level.

A second embodiment provides an application server configured todynamically determine an RS Power Boost level in a radiotelecommunication network. The application server includes a receivinginterface configured to receive network performance information andconfiguration parameters from the network; and one or more processingcircuits configured to: derive a plurality of network performanceindicators from the received performance information and configurationparameters; calculate a scaling factor based on values of the pluralityof network performance indicators; and calculate a dynamic RS PowerBoost level by applying the scaling factor to a baseline RS Power Boostlevel.

A third embodiment provides a Self-Optimized Network (SON) foroptimizing performance in the SON and an associated radio accessnetwork. The SON includes a plurality of Performance Management (PM)counters configured to measure and report network performanceinformation; a database server configured to mediate networkconfiguration parameters; and a SON application server configured todynamically determine an RS Power Boost level. The SON applicationserver includes a receiving interface configured to receive the networkperformance information from the PM counters and the configurationparameters from the database server; and one or more processing circuitsconfigured to: derive a plurality of network performance indicators fromthe performance information and configuration parameters received duringa monitoring time interval; calculate a scaling factor based on valuesof the plurality of network performance indicators; and calculate adynamic RS Power Boost level by applying the scaling factor to abaseline RS Power Boost level.

A fourth embodiment provides a computer program product comprisingprogram instructions stored on a non-transitory, computer-readablemedium in an application server. When the program instructions areexecuted by one or more processors, the application server is caused todynamically determine an RS Power Boost level in a radiotelecommunication network by monitoring a plurality of networkperformance indicators; calculating a scaling factor based on values ofthe plurality of network performance indicators; and calculating adynamic RS Power Boost level by applying the scaling factor to abaseline RS Power Boost level. The computer-readable medium may be apermanent or rewritable memory within the application server or locatedexternally. The respective computer program may also be transferred tothe application server, for example via a cable or a wireless link as asequence of signals.

The present disclosure overcomes the problems that arise from utilizingthe conventional fixed value of 3 dB for the Cell Specific ReferenceSignal (CRS) Power Boost. By monitoring a number of Key PerformanceIndicators (KPIs) and comparing the KPIs with user-defined thresholds, ascaling factor for the RS Power Boost is dynamically and intelligentlydetermined and applied to the RS Power Boost. As a result, unnecessarycoverage overlap can be prevented, leading to optimal management ofinter-cell interference. The dynamic RS Power Boost also helps toachieve optimal throughput by providing a stronger reference signal tothe most deserving users, and potentially reduces the risk of anincreased Random Access Channel (RACH) Failure Rate due to coverageimbalance between the Uplink and Downlink. Further features and benefitsof embodiments of the disclosure will become apparent from the detaileddescription below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following section, the disclosure makes reference to exemplaryembodiments illustrated in the figures, in which:

FIG. 1 is a diagram depicting time-frequency resource grids with typicalCell-specific Reference Signal (CRS) positions for one-antenna port andtwo-antenna port configurations;

FIG. 2 is a simplified block diagram of an exemplary embodiment of apartial network architecture in which a Self-Optimized Network (SON)Application Server is modified according to the present disclosure;

FIG. 3 provides a graphical depiction of how the Average DL CQIThreshold factor (AvgDlCqiThreshFactor) is evaluated;

FIG. 4 provides a graphical depiction of how the Average UL SINRThreshold factor (AvgUlSinrThreshFactor) is evaluated;

FIG. 5 is a flow chart illustrating the steps of an exemplary embodimentof the method of the present disclosure; and

FIG. 6 is a simplified block diagram of a SON Application Serveraccording to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. In the below, for purposes of explanationand not limitation, specific details are set forth in order to provide athorough understanding of the present invention. It will be apparent toone skilled in the art that the present invention may be practiced inother embodiments that depart from these specific details. For example,although the exemplary embodiments are described in connection withGSM/UMTS/LTE standard terminology to illustrate the present invention,they are equally applicable to other kinds of mobile communicationsystems. Further, the term User Equipment (UE) used herein may be anykind of mobile communication device like a mobile telephone, a PersonalDigital Assistant (PDA), a network card, a laptop or any other mobilecommunication apparatus which is capable of communicating wirelessly(via an air interface) or wired with a network.

Those skilled in the art will further appreciate that the functionsexplained herein below may be implemented using hardware circuitry,software means, or a combination thereof. The software means may be inconjunction with a programmed microprocessor or a general purposecomputer, using an Application Specific Integrated Circuit (ASIC) and/orDigital Signal Processors (DSPs). It will also be apparent that when thepresent invention is described as a method, it may also be embodied in acomputer processor and a non-transitory memory coupled to the processor,wherein the memory is encoded with one or more programs that perform themethod when executed by the processor.

FIG. 2 is a simplified block diagram of an exemplary embodiment of apartial network architecture 20 in which a Self-Optimized Network (SON)Application Server 21 is modified according to the present disclosure.Based on traffic loads reported by Performance Management (PM) counters22 in the nodes of the network and configuration parameters mediated inthe database server 23, certain Key Performance Indicators (KPIs) aremonitored and compared with user-defined thresholds to determine KPIthreshold factors that may be set, for example, in the SON ApplicationServer 21. A monitoring period, which may be user defined, may range,for example, from 15 minutes to two or three days based on dataavailability and server capacity used for this purpose. For any SONalgorithm, the accuracy increases with the confidence interval, so alonger confidence interval is preferred when resources are available tosupport the measurement process.

The KPIs threshold factors may include the following:

1. AvgDlCqiThreshFactor

2. AvgUlSinrThreshFactor

3. AvgUlRssiThreshFactor

4. MaxTaThreshFactor

5. PHRThreshFactor

6. MaxUlDlBlerThreshFactor

7. PrbUlDlUtilizationThresh Factor

8. PrachFailTdThreshFactor

9. ConnectUsersThreshFactor

10. IntraLteNbrThreshFactor

11. MimoModeThreshFactor

The KPIs may be continually monitored at the cell level as inputs to theprocess of dynamically determining a desired level of RS Power Boost.The value of each associated KPI threshold factor is set to either 0 or1, depending on the evaluation of each KPI threshold factor as describedbelow.

1. Average DL CQI Threshold Factor (AvgDlCqiThreshFactor):

FIG. 3 provides a graphical depiction of how the Average DL CQIThreshold factor (AvgDlCqiThreshFactor) is evaluated. TheAvgDlCqiThreshFactor is computed based on the degree of deviationbetween the Current Running Average DL CQI and the Average DL CQIThreshold set for RS Power Boost computation purposes. Thus:AvgDlCqiThreshFactorEval=[(Current Running Avg CQI−Avg DL CQIThreshold)/(Max DL CQI−Avg DL CQI Threshold)]

If the value is positive, i.e., Current Running Average CQI Value ishigher than the Average DL CQI Threshold, set AvgDlCqiThreshFactor=1.

If the value is negative, i.e., Current Running Average CQI Value isless than the Average DL CQI Threshold, set AvgDlCqiThreshFactor=0

It is imperative to increase the Power boost for cases where the currentrunning CQI has high values.

2. Average UL SINR Threshold Factor (AvgUlSinrThreshFactor):

FIG. 4 provides a graphical depiction of how the Average UL SINRThreshold factor (AvgUlSinrThreshFactor) is evaluated. TheAvgUlSinrThreshFactor is computed based on the degree of deviationbetween the Current Running Average UL SINR and the Average UL SINRThreshold set for RS Power Boost computation purposes. Thus:AvgulSinrThreshFactorEval=[(Current Running Avg UL SINR−Avg UL SINRThreshold)/(Max UL SINR−Avg UL SINR Threshold)]

If the value is positive, i.e., Current Running Average UL SINR Value ishigher than the Average UL SINR Threshold, set AvgUlSinrThreshFactor=1.

If the value is negative, i.e., Current Running Average UL SINR Value isless than the Average UL SINR Threshold, set AvgUlSinrThreshFactor=0

It is imperative to increase the Power boost for cases where the currentrunning UL SINR has high values.

3. Average UL RSSI Threshold Factor (AvgUlRssiThreshFactor):

The AvgUlRssiThreshFactor is computed based on the degree of deviationbetween the Current Running Average UL RSSI and the Average UL RSSIThreshold set for RS Power Boost computation purposes.

When the Current Running Average UL RSSI Value is higher than theAverage UL RSSI Threshold, set AvgUlRssiThreshFactor=0.

When the Current Running Average UL RSSI Value is lower than the AverageUL RSSI Threshold, set AvgUlRssiThreshFactor=1.

The objective is to give preference for cells exhibiting low UL RSSIvalues for setting a higher RS Power Boost value.

4. Max Timing Advance Value Threshold Factor (MaxTaThreshFactor):

Whenever the UE has DL Data to receive or UL Data to send, the UE needsto establish a Radio Resource Control (RRC) connection with the eNB. TheUE transmits a Random Access Preamble, and the eNB estimates thetransmission timing of the UE based on this transmission. The eNB thentransmits a Random Access Response, which includes a timing advancecommand. Based on that command, the UE adjusts its transmit timing.

The timing advance is initiated from the Evolved Universal TerrestrialRadio Access Network (E-UTRAN) with a Media Access Control (MAC) messagethat identifies an adjustment of the timing advance. TheMaxTaThreshFactor is computed based on the degree of deviation betweenthe Current Running Max Timing Advance value and the maximum allowedTiming Advance Threshold set based on the predetermined allowed maximumcell size in a defined interval.

When the Current Running Max Timing Advance value is higher than themaximum allowed Timing Advance Threshold in a defined time interval, setMaxTaThreshFactor=0.

When the Current Running Max Timing Advance value is lower than themaximum allowed Timing Advance Threshold in a defined time interval, setMaxTaThreshFactor=1.

The objective is to give preference for cells exhibiting low TA valuesfor setting a higher RS Power Boost value.

5. Power Headroom Report Threshold Factor (PHRThreshFactor):

The UE reports power headroom measurements in order to inform the uplinkpacket scheduler in the eNodeB how close the UE is operating to itsmaximum power capabilities. That is, the power headroom indicates howmuch transmission power remains for a UE to use in addition to the powerbeing used by the current transmission. The eNodeB (RBS) uses thisreported value to estimate how much uplink bandwidth a UE can use for aspecific subframe. When more resource blocks are scheduled for the UE,higher UE transmit power is required. However, the UE transmit powercannot exceed the UE max transmit power capability. So the UE cannot usemuch resource block (bandwidth) if the UE does not have enough powerheadroom.

The eNodeB (RBS) monitors the number of times the Power Headroom Reportfrom the UE is close to zero with the minimum Physical Resource Block(PRB) allocation (for example, for an instance with 2 UL-SCH PRB) alongwith the least MCS assigned. This counter is an indication that the ULPath loss corresponds to the maximum allowable value (cell edge UEs).The PHRThreshFactor is computed based on the degree of closeness to thePHR Threshold counter value.

When the Tbs Power Restricted counter value does not exceed the PHRThreshold Value during the monitoring interval, set PHRThreshFactor=1.

When the Tbs Power Restricted counter value exceeds the PHR ThresholdValue during the monitoring interval, set PHRThreshFactor=0.

6. BLER Threshold Factor (MaxUlDlBlerThreshFactor):

The Block Error Rate (BLER) Threshold factor in both the Uplink andDownlink is a measure of an in-sync or out-of-sync indication duringradio link monitoring. The maximum of either the Uplink or the DownlinkBLER Threshold factor value is considered for purposes of computing theRS Power Boost Computation.

When the Average DL/UL BLER Threshold Counter Value is not reachedduring the monitoring interval, set MaxUlDlBlerThreshFactor=1.

When the Average DL/UL BLER Threshold Counter Value is exceeded duringthe monitoring interval, set MaxUlDlBlerThreshFactor=0.

The objective is to give preference for cells exhibiting low DL/UL BLERvalues for setting a higher RS Power Boost value.

7. PRB/SCH Utilization Factor (PrbUIDIUtilizationThreshFactor):

The PrbUIDIUtilizationThreshFactor is computed based on the degree ofdeviation between the Current Running Average UL/DL PRB Utilization andthe Average UL/DL PRB Utilization Threshold set for RS Power Boostcomputation purposes in a predefined time interval. Thus:

PrbUIDIUtilizationThreshFactor  E val  =         [(Average  UL/DL  PRB  Utilization  Threshold − Current  Running  Avg  PRB  Utilization)/(Average  UL/DL  PRB  Utilization  Threshold − Min  PRB  Utilization)]

When the Current Running Average UL/DL PRB Utilization Value is lowerthan the Average UL/DL PRB Utilization Threshold, setPrbUIDIUtilizationThreshFactor=1.

When the Current Running Average UL/DL PRB Utilization Value is higherthan the Average UL/DL PRB Utilization Threshold, setPrbUIDIUtilizationThreshFactor=0, indicating that RS Power Boost is notrequired at this point.

8. RACH Failure Rate Threshold Factor (PrachFailTdThreshFactor):

Whenever the UE has DL Data to receive or UL Data to send, the UE needsto establish an RRC connection with the eNodeB. The UE transmits aRandom Access Preamble, and the eNodeB estimates the transmission timingof the terminal based on the Preamble. The eNodeB then transmits aRandom Access Response, which includes a timing advance and a powercontrol command. Based on the Response, the UE adjusts its transmittiming and its transmit Power.

The PrachFailTdThresh counter is incremented if the eNodeB is unable todecode any information in the assigned UL grant. This may occur when theUE is unable to meet either the timing advance or the commanded UEtransmit power due to its distance from the eNodeB. In this case, thecell is categorized as covering a larger footprint if thePrachFailTdThresh value is reached or exceeded, and RS Boost Power shallnot be recommended.

When the PrachFailTdThresh Counter Value is not reached during themonitoring interval, set PrachFailTdThreshFactor=1.

When the PrachFailTdThresh Counter Value is exceeded during themonitoring interval, set PrachFailTdThreshFactor=0.

9. Connected Users Limit Threshold Factor (ConnectUsersThreshFactor):

The ConnectUsersThreshFactor indicates a limit for the number ofconnected users.

When the ConnectUsers Threshold Counter Value is not exceeded during themonitoring interval, set ConnectUsersThreshFactor=1.

When the Connect Users Threshold Counter Value is exceeded during themonitoring interval, set ConnectUsersThreshFactor=0.

10. IntraLTE Neighbor Threshold Factor (IntraLteNbrThreshFactor):

The IntraLteNbrThreshold indicates a limit for the Intra-LTE NeighborThreshold.

When the number of defined intra-LTE neighbors is less than theIntraLteNbrThreshold, set IntraLteNbrThreshFactor=1.

When the number of defined intraLTE neighbors is greater than theIntraLteNbrThreshold, set IntraLteNbrThreshFactor=0.

The RS Power Boost should be discouraged for cell sites with a maximumNeighbor List because it could lead to potential interference.

11. MIMO Mode Threshold Factor (MimoModeThreshFactor):

The MimoModeThreshold indicates a limit for the MIMO Mode (SpatialMultiplexing) Activity Threshold.

A TxRankDistribution counter gives detailed information on how much eachtransmission mode and rank is used in regards to Transmit Diversity:Open Loop SM Rank 1; Open Loop SM Rank 2; Closed Loop SM Rank 1; ClosedLoop SM Rank 2.

When the value of the TxRankDistribution counter for MIMO exceeds thevalue of the MimoModeThreshold, set MimoModeThreshFactor=1.

When the value of the TxRankDistribution counter for MIMO does notexceed the value of the MimoModeThreshold, set MimoModeThreshFactor=0.

The RS Power Boost should be discouraged for cell sites that are alreadyoperating in transmit diversity mode most of the time for coveragepurposes.

FIG. 5 is a flow chart illustrating the steps of an exemplary embodimentof the method of the present disclosure. In this embodiment, the RSPower Boost value is given a maximum possible value of 3 dB. Accordingto the disclosure, this maximum 3 dB value is scaled downward by ascaling factor, which is determined as a function of the factorsdescribed above.

The method starts at step 31 and moves to step 32 where it is determinedwhether RS Power Boost is activated. If not, the process ends at step36. However, when RS Power Boost is activated, the method moves to step33 where the KPIs are monitored for the user-defined interval and thevalue of each KPI threshold factor (1 or 0) is determined. At step 34,the scaling factor is calculated. In this embodiment, the scaling factoris calculated as the average of the eleven KPI threshold factorsdescribed above. Thus:

Scaling  Factor = Average[AvgDICqiThreshFactor, AvgulSinrThreshFactor, AvgUIRssiThreshFactor, MaxTaThreshFactor, PHRThreshFactor, MaxUIDIBlerThreshFactor, PrbUIDIUtilzationThreshFactor, PrachFailTdThreshFactor, ConnectUsersThreshFactor, IntraLteNbrThreshFactor, MimoModeThreshFactor].

For example, if the sum of the eleven KPI threshold factors is 6 (i.e.,six of the KPI threshold factors have a value of 1, and five of thefactors have a value of 0), the scaling factor would be 0.545 (i.e.,6/11).

In other embodiments, fewer of the eleven KPI threshold factors may beutilized for calculating the scaling factor, although utilizing alleleven may provide a more optimal result. Additional factors may also bedefined and included in the calculation. In one embodiment, additionalfactors may be created by mixing the above KPI's in differentproportions. In some embodiments, different weightings may be applied toeach KPI threshold factor to bias the decision based on coverage ornetwork capacity limits. The Scaling Factor is then calculated using theweighted average of the KPI threshold factors.

The method then moves to step 35 where the dynamic RS Power Boost valueis calculated. In one exemplary embodiment, the scaling factor iscalculated as:Dynamic RS Power Boost Value=3 dB*Scaling Factor

The value of 3 dB is the maximum allowed RS Power Boost level and isused as a baseline level, which is scaled downward in this embodiment.Using the example above, where the sum of the eleven KPI thresholdfactors is 6 and the scaling factor is 0.545, the Dynamic RS Power BoostValue would then be:3 dB*0.545=1.636 dB.

As can be appreciated, other ways of dynamically adjusting the RS PowerBoost level can also be envisioned based on the above disclosure and areconsidered to be within the scope of the present disclosure. Forexample, a baseline value may be utilized where there is no boost to thenormal RS transmit power level. For each KPI threshold factor having anassigned value of 1, the RS transmit power level is increased (boosted)an appropriate amount. In one such embodiment, where the eleven KPIthreshold factors described above are considered, and the maximumallowable increase in the RS transmit power is 3 dB, the RS transmitpower level may be boosted by approximately 9.09 percent of the baselinelevel for each KPI threshold factor having an assigned value of 1. TheRS Power Boost level may be calculated by multiplying the average of theKPI threshold factors by the normal RS transmit power level and thenadding this result to the normal RS transmit power level). In this way,when all eleven KPI threshold factors are assigned a value of 1, the RSPower Boost level is doubled (i.e., increased by 3 dB).

Thus, in this embodiment, the Dynamic RS Power Boost Value (DRSPBV) iscalculated as:DRSPBV=Normal RS Power Level*(1+(Average[KPI threshold factor values]).

FIG. 6 is a simplified block diagram of the SON Application Server 21according to an exemplary embodiment of the present disclosure. Thefunctions of the SON Application Server may be controlled by one or moreprocessors 41 executing computer program instructions stored in anassociated memory. A receiving interface 42 receives network performanceinformation from the PM counters 22 and receives configurationparameters from the configuration database server 23. A timer 43provides the monitoring time interval for collection of the performanceinformation. The receiving interface may supply the information to theprocessor 41 and/or directly to a KPI deriving circuit 44. The KPIderiving unit derives a number of network KPIs from the informationreceived from the PM counters and the configuration database server.Further values for each KPI such as the maximum, minimum, or averagevalue of the KPI during the monitoring time interval may then bedetermined, and compared against an associated threshold to determine acorresponding number of KPI threshold factors. Values of 1 or 0 areassigned to each corresponding KPI threshold factor, depending upon theoutcome of the threshold comparison.

The KPI threshold values are provided to a scaling factor calculatingcircuit 45, which calculates the scaling factor from the assigned KPIthreshold values, for example by calculating the average of the assignedvalues.

The scaling factor is provided to a dynamic RS Power Boost calculatingunit 46, which calculates the dynamic RS Power Boost level by applyingthe scaling factor to the baseline RS Power Boost level.

Thus, as shown and described, a Scaling Factor value may be computed bythe SON Server and dynamically altered based on the monitored networkperformance factors and their respective predefined threshold values.The scaling factor may then be utilized to dynamically control the levelof RS Power Boost.

In the drawings and specification, there have been disclosed typicalpreferred embodiments of the invention and, although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the invention being set forthin the following claims.

What is claimed is:
 1. A method performed in a Self-Optimized Network(SON) Application Server for dynamically determining a Reference Signal(RS) Power Boost level in a radio telecommunication network, the methodcomprising: monitoring a plurality of network performance indicators fora monitoring time interval; calculating a scaling factor based on valuesof the plurality of network performance indicators measured or computedduring the monitoring time interval; and calculating a dynamic RS PowerBoost level by applying the scaling factor to a baseline RS Power Boostlevel; wherein calculating the scaling factor based on values of theplurality of network performance indicators includes: evaluating theplurality of network performance indicators to determine a correspondingplurality of performance threshold factors, wherein each given networkperformance indicator is evaluated to determine whether the value of thegiven network performance indicator during the monitoring intervalcauses an associated threshold to be exceeded; when the associatedthreshold is exceeded, assigning a first value to a performancethreshold factor corresponding to the given network performanceindicator; when the associated threshold is not exceeded, assigning adifferent, second value to the performance threshold factorcorresponding to the given network performance indicator; andcalculating the scaling factor based on the assigned values of theplurality of performance threshold factors corresponding to theplurality of network performance indicators.
 2. The method according toclaim 1, wherein: monitoring includes monitoring the plurality ofnetwork performance indicators for a monitoring time interval; andcalculating the scaling factor includes calculating the scaling factorbased on values of the plurality of network performance indicatorsmeasured or computed during the monitoring time interval.
 3. The methodaccording to claim 2, wherein the monitoring time interval isuser-defined and is in a range of 15 minutes to three days.
 4. Themethod according to claim 1, wherein each of the performance thresholdfactors is assigned a value of 1 or
 0. 5. The method according to claim4, wherein calculating the scaling factor based on the assigned valuesof the plurality of performance threshold factors includes calculatingan average of the values assigned to the plurality of performancethreshold factors to obtain the scaling factor.
 6. The method accordingto claim 5, wherein the baseline RS Power Boost level is a maximumallowed RS Power Boost value, and calculating the dynamic RS Power Boostlevel includes multiplying the maximum allowed RS Power Boost value indecibels, dB, by the calculated scaling factor; wherein the dynamic RSPower Boost level indicates the amount in dB that a normal RS transmitpower level is to be boosted.
 7. The method according to claim 5,wherein the baseline RS Power Boost level is a normal RS transmit powerlevel, and calculating the dynamic RS Power Boost level includesmultiplying the normal RS transmit power level by the calculated scalingfactor to obtain a result; wherein the result is added to the normal RStransmit power level to achieve a boosted RS transmit power level. 8.The method according to claim 1, wherein monitoring includes monitoringat least one network performance indicator selected from a groupconsisting of: Average Downlink (DL) Channel Quality Indicator (CQI)Threshold Factor (AvgDlCqiThreshFactor); Average Uplink (UL) Signal toInterference and Noise Ratio (SINR) Threshold Factor(AvgUlSinrThreshFactor); Average UL Received Signal Strength Indicator(RSSI) Threshold Factor (AvgUlRssiThreshFactor); Maximum Timing AdvanceValue Threshold Factor (MaxTaThreshFactor); Power Headroom ReportThreshold Factor (PHRThreshFactor); Maximum UL/DL Block Error Rate(BLER) Threshold Factor (MaxUlDlBlerThreshFactor); Physical ResourceBlock Scheduling (PRB/SCH) Utilization Factor(PrbUIDIUtilizationThreshFactor); Random Access Channel (RACH) FailureRate Threshold Factor (PrachFailTdThreshFactor); Connected Users LimitThreshold Factor (ConnectUsersThreshFactor); IntraLTE Neighbor ThresholdFactor (IntraLteNbrThreshFactor); and Multiple Input Multiple Output(MIMO) Mode Threshold Factor (MimoModeThreshFactor).
 9. The methodaccording to claim 8, wherein calculating the scaling factor includescalculating an average of the values of the monitored networkperformance indicators.
 10. A Self-Optimized Network (SON) ApplicationServer configured to dynamically determine a Reference Signal (RS) PowerBoost level in a radio telecommunication network, the SON ApplicationServer comprising: a receiving interface configured to receive networkperformance information and configuration parameters from the networkfor a monitoring time interval; and one or more processing circuitsconfigured to: derive a plurality of network performance indicators fromthe received performance information and configuration parameters;calculate a scaling factor based on values of the plurality of networkperformance indicators measured or computed during the monitoring timeinterval; and calculate a dynamic RS Power Boost level by applying thescaling factor to a baseline RS Power Boost level; wherein the one ormore processing circuits are further configured to calculate the scalingfactor based on values of the plurality of network performanceindicators by performing the following: evaluating the plurality ofnetwork performance indicators to determine a corresponding plurality ofperformance threshold factors, wherein each given network performanceindicator is evaluated to determine whether the value of the givennetwork performance indicator during the monitoring interval causes anassociated threshold to be exceeded; when the associated threshold isexceeded, assigning a first value to a performance threshold factorcorresponding to the given network performance indicator; when theassociated threshold is not exceeded, assigning a different, secondvalue to the performance threshold factor corresponding to the givennetwork performance indicator; and calculating the scaling factor basedon the assigned values of the plurality of performance threshold factorscorresponding to the plurality of network performance indicators. 11.The SON Application Server according to claim 10, wherein the one ormore processing circuits are configured to: monitor the plurality ofnetwork performance indicators for a monitoring time interval; andcalculate the scaling factor based on values of the plurality of networkperformance indicators measured or computed during the monitoring timeinterval.
 12. The application server according to claim 11, wherein themonitoring time interval is user-defined and is in a range of 15 minutesto three days.
 13. The SON Application Server according to claim 10,wherein each of the performance threshold factors is assigned a value of1 or
 0. 14. The SON Application Server according to claim 13, whereinthe one or more processing circuits are further configured to calculatethe scaling factor by calculating an average of the values assigned tothe plurality of performance threshold factors to obtain the scalingfactor.
 15. The SON Application Server according to claim 14, whereinthe baseline RS Power Boost level is a maximum allowed RS Power Boostvalue, and the one or more processing circuits are configured tocalculate the dynamic RS Power Boost level by multiplying the maximumallowed RS Power Boost value in decibels, dB, by the calculated scalingfactor; wherein the dynamic RS Power Boost level indicates the amount indB that a normal RS transmit power level is to be boosted.
 16. The SONApplication Server according to claim 14, wherein the baseline RS PowerBoost level is a normal RS transmit power level, and the one or moreprocessing circuits are configured to calculate the dynamic RS PowerBoost level by multiplying the normal RS transmit power level by thecalculated scaling factor to obtain a result; wherein the result isadded to the normal RS transmit power level to achieve a boosted RStransmit power level.
 17. The SON Application Server according to claim10, wherein the plurality of network performance indicators are selectedfrom a group consisting of: Average Downlink (DL) Channel QualityIndicator (CQI) Threshold Factor (AvgDlCqiThreshFactor); Average Uplink(UL) Signal to Interference and Noise Ratio (SINR) Threshold Factor(AvgUlSinrThreshFactor); Average UL Received Signal Strength Indicator(RSSI) Threshold Factor (AvgUlRssiThreshFactor); Maximum Timing AdvanceValue Threshold Factor (MaxTaThreshFactor); Power Headroom ReportThreshold Factor (PHRThreshFactor); Maximum UL/DL Block Error Rate(BLER) Threshold Factor (MaxUlDlBlerThreshFactor); Physical ResourceBlock Scheduling (PRB/SCH) Utilization Factor(PrbUIDIUtilizationThreshFactor); Random Access Channel (RACH) FailureRate Threshold Factor (PrachFailTdThreshFactor); Connected Users LimitThreshold Factor (ConnectUsersThreshFactor); IntraLTE Neighbor ThresholdFactor (IntraLteNbrThreshFactor); and Multiple Input Multiple Output(MIMO) Mode Threshold Factor (MimoModeThreshFactor).
 18. The SONApplication Server according to claim 17, wherein the one or moreprocessing circuits are configured to calculate the scaling factor bycalculating an average of the values of the network performanceindicators.
 19. A Self-Optimized Network (SON) for optimizingperformance in the SON and an associated radio access network, the SONcomprising: a plurality of Performance Management (PM) countersconfigured to measure and report network performance information; adatabase server configured to mediate network configuration parameters;and a SON application server configured to dynamically determine aReference Signal (RS) Power Boost level, the SON application servercomprising: a receiving interface configured to receive the networkperformance information from the PM counters and the configurationparameters from the database server for a monitoring time interval; andone or more processing circuits configured to: derive a plurality ofnetwork performance indicators from the performance information andconfiguration parameters received during a monitoring time interval;calculate a scaling factor based on values of the plurality of networkperformance indicators measured or computed during the monitoring timeinterval; and calculate a dynamic RS Power Boost level by applying thescaling factor to a baseline RS Power Boost level; wherein the one ormore processing circuits are further configured to calculate the scalingfactor based on values of the plurality of network performanceindicators by performing the following: evaluating the plurality ofnetwork performance indicators to determine a corresponding plurality ofperformance threshold factors, wherein each given network performanceindicator is evaluated to determine whether the value of the givennetwork performance indicator during the monitoring interval causes anassociated threshold to be exceeded; when the associated threshold isexceeded, assigning a first value to a performance threshold factorcorresponding to the given network performance indicator; when theassociated threshold is not exceeded, assigning a different, secondvalue to the performance threshold factor corresponding to the givennetwork performance indicator; and calculating the scaling factor basedon the assigned values of the plurality of performance threshold factorscorresponding to the plurality of network performance indicators. 20.The SON Application Server according to claim 19, wherein the pluralityof network performance indicators are selected from a group consistingof: Average Downlink (DL) Channel Quality Indicator (CQI) ThresholdFactor (AvgDlCqiThreshFactor); Average Uplink (UL) Signal toInterference and Noise Ratio (SINR) Threshold Factor(AvgUlSinrThreshFactor); Average UL Received Signal Strength Indicator(RSSI) Threshold Factor (AvgUlRssiThreshFactor); Maximum Timing AdvanceValue Threshold Factor (MaxTaThreshFactor); Power Headroom ReportThreshold Factor (PHRThreshFactor); Maximum UL/DL Block Error Rate(BLER) Threshold Factor (MaxUlDlBlerThreshFactor); Physical ResourceBlock Scheduling (PRB/SCH) Utilization Factor(PrbUIDIUtilizationThreshFactor); Random Access Channel (RACH) FailureRate Threshold Factor (PrachFailTdThreshFactor); Connected Users LimitThreshold Factor (ConnectUsersThreshFactor); IntraLTE Neighbor ThresholdFactor (IntraLteNbrThreshFactor); and Multiple Input Multiple Output(MIMO) Mode Threshold Factor (MimoModeThreshFactor).
 21. The SONApplication Server according to claim 20, wherein the one or moreprocessing circuits are configured to calculate the scaling factor bycalculating an average of the values of the network performanceindicators.